WASHINGTON (AP) — With no weekend breakthrough to end a prolonged partial government shutdown, President Donald Trump is standing firm in his border wall funding demands and newly empowered House Democrats are planning to step up pressure on Trump and Republican lawmakers to reopen the government.

Trump showed no signs of budging on his demand for more than $5 billion for a wall along the U.S.-Mexico border, though on Sunday he did offer to build it with steel rather than concrete, a concession Democrats panned.

With the shutdown lurching into a third week, many Republicans watched nervously from the sidelines as hundreds of thousands of federal workers went without pay and government disruptions hit the lives of ordinary Americans.

White House officials affirmed Trump’s funding request in a letter to Capitol Hill after a meeting Sunday with senior congressional aides led by Vice President Mike Pence at the White House complex yielded little progress. The letter from Office of Management and Budget Acting Director Russell Vought sought funding for a “steel barrier on the Southwest border.”

The White House said the letter, as well as details provided during the meeting, sought to answer Democrats’ questions about the funding request. Democrats, though, said the administration still failed to provide a full budget of how it would spend the billions requested for the wall from Congress. Trump campaigned on a promise that Mexico would pay for the wall, but Mexico has refused.

The letter includes a request for $800 million for “urgent humanitarian needs,” a reflection of the growing anxiety over migrants traveling to the border — which the White House said Democrats raised in the meetings. And it repeats some existing funding requests for detention beds and security officers, which have already been panned by Congress and would likely find resistance among House Democrats.

Trump sought to frame a steel barrier as progress, saying Democrats “don’t like concrete, so we’ll give them steel.” The president has already suggested his definition of the wall is flexible, but Democrats have made clear they see a wall as immoral and ineffective and prefer other types of border security funded at already agreed upon levels.

House Speaker Nancy Pelosi intends to begin passing individual bills to reopen agencies in the coming days, starting with the Treasury Department to ensure people receive their tax refunds. That effort is designed to squeeze Senate Republicans, some of whom are growing increasingly anxious about the extended shutdown.

Among the Republicans expressing concerns was Sen. Susan Collins, R-Maine, who said Senate Majority Leader Mitch McConnell should take up bills from the Democratic-led House.

“Let’s get those reopened while the negotiations continue,” Collins said on NBC’s “Meet the Press.”

Adding to concerns, federal workers might miss this week’s paychecks. Acting chief of staff Mick Mulvaney said on NBC’s “Meet the Press” that if the shutdown continues into Tuesday, “then payroll will not go out as originally planned on Friday night.”

Trump reaffirmed that he would consider declaring a national emergency to circumvent Congress and spend money as he saw fit. Such a move would seem certain to draw legal challenges.

Incoming House Armed Services Committee Chairman Adam Smith, D-Wash., said on ABC’s “This Week” that the executive power has been used to build military facilities in Iraq and Afghanistan but would likely be “wide open” to a court challenge for a border wall. Speaking on CNN’s “State of the Union,” Intelligence Committee Chairman Adam Schiff called the idea a “nonstarter.”

Trump asserted that he could relate to the plight of the hundreds of thousands of federal workers who aren’t getting paid, though he acknowledged they will have to “make adjustments” to deal with the shutdown shortfall.

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Associated Press writer Julie Walker in New York, Jill Colvin in Washington and Elliot Spagat in San Diego contributed to this report.